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I have a RPi zero W and am reading four ds18b20 temperature sensors (with a 10K ohm resistor between the data and vcc line). Now and then I keep getting "SensorNotReadyError" from the sensors.

My previous design had one sensor less and didn't have an additional LED and it worked fine. Could it be that the LED + additional sensor consume too much power? I'm using a 2A power brick. Could a 3A solve the problem? Any ideas how to read 4+ sensors with a Rpi zero?

tlfong01
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Jake B.
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3 Answers3

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A suggested pull up resistor is 4.7K ohm. Current of the sensor is not an issue as its active current is 1mA. Try with the above mentioned resistor value.

theashwanisingla
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These sensors require only a few milliamps to operate. I do not believe the power supply is the problem.

I would use the suggested 4k7 pull-up to 3V3 rather than 10k.

joan
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The sensor needs a pull up resistor. I would suggest using something in the 3.9K range although 4.7 K should work depending on wire length. Also they do not work very well in parasitic mode at 3.3 volts. Your error indicates it does not have enough power to operate.

Gil
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